Workers have discovered a possible mass grave with 49 human skulls during two weeks of excavations on a construction site in central Sri Lanka.

Police spokesman Prishantha Jayakody said Friday the skulls plus other bones were found during excavation work for an extension on a hospital in Matale town.

Jayakody said other details about the bones and the burial site were immediately not known.

But the People's Liberation Front, a Marxist group that carried out two armed insurrections, called for an investigation to see if the site is a mass grave where its members were buried after being killed by government soldiers.

Matale was one of the areas where the Marxist rebels, mostly from ethnic Sinhalese majority, were active during their rebellions in 1971 and 1988-89, both which were crushed by government forces with heavy casualties on both sides.

It was common to see bodies of rebels taken by government paramilitaries burning along the sides of roads or floating in rivers or lakes.

Jayakody said an investigation will start son to determine when the people died.